The objective of this study is to characterize the biological activities of certain bacterial-encoded DNA binding proyeins. These proyeins include IHF, ahe product of yhe himA and hip genes, and the B subunit of DNA gyrase, encoded by the gyrB gene, which were originally identified by their roles in the site-specific recombination reaction leading to integration of the coliphage lambda genome into the E. coli chromosome. A number of studies directed towards this goal are outlined: 1) By employing mutants defective in one or more of these genes, the roles of the proteins in site-specific recombination, gene expression, transposition of genetic elements and plasmid maintenance will be studied. 2) Using both in vivo and in vitro recombination techniques, hybrid himA-hip genes will be generated and the biological activity of the resulting chimeric proteins will be studied in order to relate structure to function of the IHF subunits. 3) The roles of IHF and a newly identified alternative host factor in cleavage and packaging of phage DNA will be explored by analyzing lambda mutants that overcome blocks in these reactions imposed by himA-hip and gyrB mutations as well as site mutations on the Lambda genome. 4) Additional factors required for IHF and/or Gyr activity will be searched for by selecting mutations that suppress the effect of himA-hip and gyrB mutations on gene expression. 5) Possible himA and hip genes from other bacterial species will be identifed by DNA hybridization and molecular cloning. Use of this model system should provide general information useful to the analysis of viral integration and gene expression in malignant transformation. These studies should also yield information on the factors involved in the transposition of genetic elements such as those encoding antibiotic resistance markers.